How Asbestos Causes Mesothelioma

How asbestos fibers enter the lungs

Asbestos is a term for a group of magnesium silicates that have fibrous structure. Asbestos minerals consist of fibers that are easily separable. Individual fibers are extremely small and fine, light enough to be carried in the air. Doctors who treat lung disease consider all forms of asbestos dangerous, and capable of causing cancer. The six most common are amosite, chrysotile, crocidolite, and the fibrous varieties of tremolite, actinolite, and anthophyllite. Amphibole forms of asbestos, whose fibers are straight, are more likely to cause disease than chrysotile, whose fibers are curved.

In the course of mining, manufacturing and installing products using asbestos, tiny fibers are dislodged and become airborne. Workers in an environment where asbestos is used cannot avoid inhaling the airborne fibers. Poor ventilation and insufficient or no protective apparatus increase exposure to this lethal fiber. Workers have described mining and factory environments where the air was white with asbestos dust, and their clothes and hair were covered within the fine white fibers.

How asbestos fibers damage the lungs

Most fibers are cleared from the lungs within hours of inhalation. Coughing carries them to the throat in a layer of mucus, where they are either spit out, or swallowed, and make their way out of the body.

Not all inhaled asbestos is cleared from the lungs. Some fibers progress into the alveoli, the tiny pockets within the lungs where oxygen is exchanged with the bloodstream. The fibers may remain for years, even the rest of a person's life. Amphibole asbestos fibers, which are longer and straighter than chrysotile fibers, tend to remain in the lung the longest.

Asbestos fibers move toward the lower portion of the lungs and the diaphragm, the large muscle that moves the lungs in breathing, which sits just under the lungs. In autopsies, most asbestos disease of the lungs is seen the bottom lobes of the lungs and on the surface of the diaphragm. Asbestos fibers which lodge in lung tissue and are not expelled continue to damage the tissue as long as they stay there, as the mesothelioma grows slowly and silently. Symptoms may not appear for 15 to 40 years after exposure.

Asbestos fibers and mesothelioma

Asbestos fibers work their way through the lungs into the pleural cavity, the space in the chest where the lungs sit. The asbestos fibers invade the mesothelium, the thin, moist, flexible tissue that lines the cavity. Mesothelioma specialists have two theories about how asbestos in the pleural cavity causes mesothelioma. One theory is that as the asbestos fibers migrate through the pleural cavity, they enter tissue walls and irritate tissues. The irritated cells respond by forming scar tissue. The mesothelial cells show an inflammatory immune response, scarring, and eventually the uncontrolled proliferation of cells that is the hallmark of cancer.

The second theory focuses on events at a molecular level, speculating that asbestos fibers interact with individual mesothelial cells, interfering with their cell division, or possibly damaging the cell's DNA during mitosis, or cell division. The part of the DNA that regulates the cells' growth and reproduction is damaged, so that reproduction is no longer controlled. Cells begin to reproduce wildly. This uncontrolled cell growth creates the thickened cancerous tissue and eventually begins to invade other organs.

Although the highest risk of developing mesothelioma comes from prolonged exposure to asbestos fiber, some people who develop mesothelioma have had only very brief exposure. The first symptoms of mesothelioma may not show up for 15, sometimes for as long as 30 or 40 years after the victim's exposure to asbestos. By the time symptoms are painful enough for a victim to seek medical attention, the disease may have progressed so far that life expectancy will be measured in months.

If you or a loved one has received a diagnosis of mesothelioma, and you believe that the mesothelioma developed as a result of workplace exposure to asbestos, you may have a legal claim against the corporation that permitted the exposure, or the manufacturer of the asbestos product. To learn more about your rights, you should consult a lawyer who specializes in asbestos claims.

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Posted in: Asbestos,Causes,Mesothelioma